The present invention relates to a shifting arrangement for an automatic transmission of a motor vehicle of the type disclosed in the DE No. 38 07 881.
A shifting arrangement for an automatic transmission of a motor vehicle is provided according to the DE No. 38 07 881 which renders realizable by means of the selector lever a program "Manual Speed Preselection" of an automatic transmission controlled by way of an electronic control apparatus according to Bosch, Technische Berichte [Technical Reports] 7 (1983) 4, Pages 160-166. A program switch which enables to the driver a selection between an economy program, a power program and a program for the manual selection of the transmission speeds by way of the selector lever can be dispensed with in that case. The transmission can be constructed more friendly as regards operation and can be manufactured in a more cost-favorable manner.
This is achieved in the first instance in that the selector lever is shiftable by way of a transverse lane into a second shifting lane parallel to the first shifting lane and in that with the displacement of the shifting lever in the second shifting lane the forward speeds (1, 2, 3, 4) of the transmission are manually engageable. In a particularly advantageous construction, the shifting lever is thereby constructed in the second shifting lane as rocker lever which during pivoting out of a stable center position (normal rest position) into the one direction initiates a shifting-down and in the other direction a shifting up of the automatic transmission.
It is the object of the present invention to further increase the operating safety of such an automatic transmission.
The underlying problems are solved according to the present invention in that the control apparatus includes a shifting unit influenced by a sensor detecting the shifting from the first shifting lane to the second shifting lane, which during an introduction of the shifting lever from the first shifting lane into the second shifting lane effects a maintenance of the actually engaged transmission speed at least for such length of time as a rotational speed of a driving internal combustion engine has not yet exceeded an upper rotational speed limit or has not yet dropped below a lower rotational speed limit, or the shifting lever has not yet been displaced in the second shifting lane.
The advantages of the present invention reside primarily in that the operating reliability and operational safety of the automatic transmission is further increased. In particular, undesired shifting operations (which come as a surprise to the driver) are thereby avoided when shifting the shifting lever from one lane into the other.
This is achieved in that a control apparatus for the control of the transmission includes a shifting unit which during the introduction of the shifting lever out of the first shifting lane into the second shifting lane effects a maintenance of the actual transmission speed at least as long as a rotational speed of a driving internal combustion engine has not yet exceeded an upper rotational speed limit or has not yet dropped below a lower rotational speed limit, or the shifting lever has not yet been displaced in the second shifting lane for the initiation of a shifting-up/shifting-down operation.
Similarly during the introduction of the shifting lever from the second shifting lane into the first shifting lane, the actually engaged transmission speed is maintained at least so long until the control apparatus has undertaken anew an automatic transmission speed adaptation or until the internal combustion engine has reached its rotational speed limits.